Medieval knighthood sounds like a romantic career in fiction. What a life of chivalry was really like doesn't seem all that great. A team of scientists tried to replicate the work of a knight clad in up to 110 pounds of metal by dressing up volunteer historical re-enactors from the Royal Armories in London, and putting them on treadmills. Even though they were used to wearing armor, you better believe they worked up a sweat!
Sure enough, the researchers found, armor was exhausting. The men used 2.3 times as much energy to walk while wearing the armor than without it, and 1.9 times as much to run. Being outfitted for battle turned out to be even more tiring than hauling around a backpack of the same weight would’ve been. As it turns out, covering your legs with enormous, heavy metal plates makes moving around a lot harder.